By Seattle Times business staff

HaloSource has completed an initial public offering on London's AIM exchange for small companies, selling $80 million in stock.

The deal raises $50 million before expenses for the Bothell-based company, and $30 million for existing shareholders who sold some stock.

HaloSource, best known for water-purifying technology built into filters or dispensers sold by other companies, said it will use the proceeds to support its expansion plans, including construction of additional manufacturing plants.